ColumnMapTranslator.cs source code in C# .NET

                        Code:
                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / DataEntity / System / Data / Query / PlanCompiler / ColumnMapTranslator.cs / 1305376 / ColumnMapTranslator.cs
                        
                        
                            //---------------------------------------------------------------------- 
// 
//      Copyright (c) Microsoft Corporation.  All rights reserved.
// 
// 
// @owner  [....]
// @backupOwner [....] 
//--------------------------------------------------------------------- 

using System; 
using System.Collections.Generic;
using System.Globalization;
using System.Data.Query.InternalTrees;
using System.Data.Query.PlanCompiler; 
using System.Linq;
//using System.Diagnostics; // Please use PlanCompiler.Assert instead of Debug.Assert in this class... 
 
namespace System.Data.Query.PlanCompiler
{ 

    /// 
    /// Delegate pattern that the ColumnMapTranslator uses to find its replacement
    /// columnMaps.  Given a columnMap, return it's replacement. 
    /// 
    ///  
    ///  
    internal delegate ColumnMap ColumnMapTranslatorTranslationDelegate(ColumnMap columnMap);
 
    /// 
    /// ColumnMapTranslator visits the ColumnMap hiearchy and runs the translation delegate
    /// you specify;  There are some static methods to perform common translations, but you
    /// can bring your own translation if you desire. 
    ///
    /// This visitor only creates new ColumnMap objects when necessary; it attempts to 
    /// replace-in-place, except when that is not possible because the field is not 
    /// writable.
    /// 
    /// NOTE: over time, we should be able to modify the ColumnMaps to have more writable
    ///       fields;
    /// 
    internal class ColumnMapTranslator : ColumnMapVisitorWithResults 
    {
 
        #region Constructors 

        ///  
        /// Singleton instance for the "public" methods to use;
        /// 
        static private ColumnMapTranslator Instance = new ColumnMapTranslator();
 
        /// 
        /// Constructor; no one should use this. 
        ///  
        private ColumnMapTranslator()
        { 
        }

        #endregion
 
        #region Visitor Helpers
 
        ///  
        /// Returns the var to use in the copy, either the original or the
        /// replacement.  Note that we will follow the chain of replacements, in 
        /// case the replacement was also replaced.
        /// 
        /// 
        ///  
        /// 
        private static Var GetReplacementVar(Var originalVar, Dictionary replacementVarMap) 
        { 
            // SQLBUDT #478509: Follow the chain of mapped vars, don't
            //                  just stop at the first one 
            Var replacementVar = originalVar;

            while (replacementVarMap.TryGetValue(replacementVar, out originalVar))
            { 
                if (originalVar == replacementVar)
                { 
                    break; 
                }
                replacementVar = originalVar; 
            }
            return replacementVar;
        }
 
        #endregion
 
        #region "Public" surface area 

        ///  
        /// Bring-Your-Own-Replacement-Delegate method.
        /// 
        /// 
        ///  
        /// 
        internal static ColumnMap Translate(ColumnMap columnMap, ColumnMapTranslatorTranslationDelegate translationDelegate) 
        { 
            return columnMap.Accept(ColumnMapTranslator.Instance, translationDelegate);
        } 

        /// 
        /// Replace VarRefColumnMaps with the specified ColumnMap replacement
        ///  
        /// 
        ///  
        ///  
        internal static ColumnMap Translate(ColumnMap columnMapToTranslate, Dictionary varToColumnMap)
        { 
            ColumnMap result = Translate(columnMapToTranslate,
                                            delegate(ColumnMap columnMap)
                                            {
                                                VarRefColumnMap varRefColumnMap = columnMap as VarRefColumnMap; 
                                                if (null != varRefColumnMap)
                                                { 
                                                    if (varToColumnMap.TryGetValue(varRefColumnMap.Var, out columnMap)) 
                                                    {
                                                        // perform fixups; only allow name changes when the replacement isn't 
                                                        // already named (and the original is named...)
                                                        if (!columnMap.IsNamed && varRefColumnMap.IsNamed)
                                                        {
                                                            columnMap.Name = varRefColumnMap.Name; 
                                                        }
                                                    } 
                                                    else 
                                                    {
                                                        columnMap = varRefColumnMap; 
                                                    }
                                                }
                                                return columnMap;
                                            } 
                                            );
            return result; 
        } 

        ///  
        /// Replace VarRefColumnMaps with new VarRefColumnMaps with the specified Var
        /// 
        /// 
        ///  
        /// 
        internal static ColumnMap Translate(ColumnMap columnMapToTranslate, Dictionary varToVarMap) 
        { 
            ColumnMap result = Translate(columnMapToTranslate,
                                            delegate(ColumnMap columnMap) 
                                            {
                                                VarRefColumnMap varRefColumnMap = columnMap as VarRefColumnMap;
                                                if (null != varRefColumnMap)
                                                { 
                                                    Var replacementVar = GetReplacementVar(varRefColumnMap.Var, varToVarMap);
                                                    if (varRefColumnMap.Var != replacementVar) 
                                                    { 
                                                        columnMap = new VarRefColumnMap(varRefColumnMap.Type, varRefColumnMap.Name, replacementVar);
                                                    } 
                                                }
                                                return columnMap;
                                            }
                                            ); 

            return result; 
        } 

        ///  
        /// Replace VarRefColumnMaps with ScalarColumnMaps referring to the command and column
        /// 
        /// 
        ///  
        /// 
        internal static ColumnMap Translate(ColumnMap columnMapToTranslate, Dictionary> varToCommandColumnMap) 
        { 
            ColumnMap result = Translate(columnMapToTranslate,
                                            delegate(ColumnMap columnMap) 
                                            {
                                                VarRefColumnMap varRefColumnMap = columnMap as VarRefColumnMap;
                                                if (null != varRefColumnMap)
                                                { 
                                                    KeyValuePair commandAndColumn;
 
                                                    if (!varToCommandColumnMap.TryGetValue(varRefColumnMap.Var, out commandAndColumn)) 
                                                    {
                                                        throw EntityUtil.InternalError(EntityUtil.InternalErrorCode.UnknownVar, 1, varRefColumnMap.Var.Id); // shouldn't have gotten here without having a resolveable var 
                                                    }
                                                    columnMap = new ScalarColumnMap(varRefColumnMap.Type, varRefColumnMap.Name, commandAndColumn.Key, commandAndColumn.Value);
                                                }
 
                                                // While we're at it, we ensure that all columnMaps are named; we wait
                                                // until this point, because we don't want to assign names until after 
                                                // we've gone through the transformations; 
                                                if (!columnMap.IsNamed)
                                                { 
                                                    columnMap.Name = ColumnMap.DefaultColumnName;
                                                }
                                                return columnMap;
                                            } 
                                            );
 
            return result; 
        }
 
        #endregion

        #region Visitor methods
 
        #region List handling
 
        ///  
        /// List(ColumnMap)
        ///  
        /// 
        /// 
        /// 
        private void VisitList(TResultType[] tList, ColumnMapTranslatorTranslationDelegate translationDelegate) 
                where TResultType : ColumnMap
        { 
            for (int i = 0; i < tList.Length; i++) 
            {
                tList[i] = (TResultType)tList[i].Accept(this, translationDelegate); 
            }
        }

        #endregion 

        #region EntityIdentity handling 
 
        /// 
        /// DiscriminatedEntityIdentity 
        /// 
        /// 
        /// 
        ///  
        protected override EntityIdentity VisitEntityIdentity(DiscriminatedEntityIdentity entityIdentity, ColumnMapTranslatorTranslationDelegate translationDelegate)
        { 
            ColumnMap newEntitySetColumnMap = entityIdentity.EntitySetColumnMap.Accept(this, translationDelegate); 
            VisitList(entityIdentity.Keys, translationDelegate);
 
            if (newEntitySetColumnMap != entityIdentity.EntitySetColumnMap)
            {
                entityIdentity = new DiscriminatedEntityIdentity((SimpleColumnMap)newEntitySetColumnMap, entityIdentity.EntitySetMap, entityIdentity.Keys);
            } 
            return entityIdentity;
        } 
 
        /// 
        /// SimpleEntityIdentity 
        /// 
        /// 
        /// 
        ///  
        protected override EntityIdentity VisitEntityIdentity(SimpleEntityIdentity entityIdentity, ColumnMapTranslatorTranslationDelegate translationDelegate)
        { 
            VisitList(entityIdentity.Keys, translationDelegate); 
            return entityIdentity;
        } 

        #endregion

        ///  
        /// ComplexTypeColumnMap
        ///  
        ///  
        /// 
        ///  
        internal override ColumnMap Visit(ComplexTypeColumnMap columnMap, ColumnMapTranslatorTranslationDelegate translationDelegate)
        {
            SimpleColumnMap newNullSentinel = columnMap.NullSentinel;
            if (null != newNullSentinel) 
            {
                newNullSentinel = (SimpleColumnMap)translationDelegate(newNullSentinel); 
            } 

            VisitList(columnMap.Properties, translationDelegate); 

            if (columnMap.NullSentinel != newNullSentinel)
            {
                columnMap = new ComplexTypeColumnMap(columnMap.Type, columnMap.Name, columnMap.Properties, newNullSentinel); 
            }
            return translationDelegate(columnMap); 
        } 

        ///  
        /// DiscriminatedCollectionColumnMap
        /// 
        /// 
        ///  
        /// 
        internal override ColumnMap Visit(DiscriminatedCollectionColumnMap columnMap, ColumnMapTranslatorTranslationDelegate translationDelegate) 
        { 
            ColumnMap newDiscriminator = columnMap.Discriminator.Accept(this, translationDelegate);
            VisitList(columnMap.ForeignKeys, translationDelegate); 
            VisitList(columnMap.Keys, translationDelegate);
            ColumnMap newElement = columnMap.Element.Accept(this, translationDelegate);

            if (newDiscriminator != columnMap.Discriminator || newElement != columnMap.Element) 
            {
                columnMap = new DiscriminatedCollectionColumnMap(columnMap.Type, columnMap.Name, newElement, columnMap.Keys, columnMap.ForeignKeys,(SimpleColumnMap)newDiscriminator, columnMap.DiscriminatorValue); 
            } 
            return translationDelegate(columnMap);
        } 

        /// 
        /// EntityColumnMap
        ///  
        /// 
        ///  
        ///  
        internal override ColumnMap Visit(EntityColumnMap columnMap, ColumnMapTranslatorTranslationDelegate translationDelegate)
        { 
            EntityIdentity newEntityIdentity = VisitEntityIdentity(columnMap.EntityIdentity, translationDelegate);
            VisitList(columnMap.Properties, translationDelegate);

            if (newEntityIdentity != columnMap.EntityIdentity) 
            {
                columnMap = new EntityColumnMap(columnMap.Type, columnMap.Name, columnMap.Properties, newEntityIdentity); 
            } 
            return translationDelegate(columnMap);
        } 

        /// 
        /// SimplePolymorphicColumnMap
        ///  
        /// 
        ///  
        ///  
        internal override ColumnMap Visit(SimplePolymorphicColumnMap columnMap, ColumnMapTranslatorTranslationDelegate translationDelegate)
        { 
            ColumnMap newTypeDiscriminator = columnMap.TypeDiscriminator.Accept(this, translationDelegate);

            // NOTE: we're using Copy-On-Write logic to avoid allocation if we don't
            //       need to change things. 
            Dictionary newTypeChoices = columnMap.TypeChoices;
            foreach (KeyValuePair kv in columnMap.TypeChoices) 
            { 
                TypedColumnMap newTypeChoice = (TypedColumnMap)kv.Value.Accept(this, translationDelegate);
 
                if (newTypeChoice != kv.Value)
                {
                    if (newTypeChoices == columnMap.TypeChoices)
                    { 
                        newTypeChoices = new Dictionary(columnMap.TypeChoices);
                    } 
                    newTypeChoices[kv.Key] = newTypeChoice; 
                }
            } 
            VisitList(columnMap.Properties, translationDelegate);

            if (newTypeDiscriminator != columnMap.TypeDiscriminator || newTypeChoices != columnMap.TypeChoices)
            { 
                columnMap = new SimplePolymorphicColumnMap(columnMap.Type, columnMap.Name, columnMap.Properties, (SimpleColumnMap)newTypeDiscriminator, newTypeChoices);
            } 
            return translationDelegate(columnMap); 
        }
 
        /// 
        /// MultipleDiscriminatorPolymorphicColumnMap
        /// 
        internal override ColumnMap Visit(MultipleDiscriminatorPolymorphicColumnMap columnMap, ColumnMapTranslatorTranslationDelegate translationDelegate) 
        {
            // At this time, we shouldn't ever see this type here; it's for SPROCS which don't use 
            // the plan compiler. 
            System.Data.Query.PlanCompiler.PlanCompiler.Assert(false, "unexpected MultipleDiscriminatorPolymorphicColumnMap in ColumnMapTranslator");
            return null; 
        }

        /// 
        /// RecordColumnMap 
        /// 
        ///  
        ///  
        /// 
        internal override ColumnMap Visit(RecordColumnMap columnMap, ColumnMapTranslatorTranslationDelegate translationDelegate) 
        {
            SimpleColumnMap newNullSentinel = columnMap.NullSentinel;
            if (null != newNullSentinel)
            { 
                newNullSentinel = (SimpleColumnMap)translationDelegate(newNullSentinel);
            } 
 
            VisitList(columnMap.Properties, translationDelegate);
 
            if (columnMap.NullSentinel != newNullSentinel)
            {
                columnMap = new RecordColumnMap(columnMap.Type, columnMap.Name, columnMap.Properties, newNullSentinel);
            } 
            return translationDelegate(columnMap);
        } 
 
        /// 
        /// RefColumnMap 
        /// 
        /// 
        /// 
        ///  
        internal override ColumnMap Visit(RefColumnMap columnMap, ColumnMapTranslatorTranslationDelegate translationDelegate)
        { 
            EntityIdentity newEntityIdentity = VisitEntityIdentity(columnMap.EntityIdentity, translationDelegate); 

            if (newEntityIdentity != columnMap.EntityIdentity) 
            {
                columnMap = new RefColumnMap(columnMap.Type, columnMap.Name, newEntityIdentity);
            }
            return translationDelegate(columnMap); 
        }
 
        ///  
        /// ScalarColumnMap
        ///  
        /// 
        /// 
        /// 
        internal override ColumnMap Visit(ScalarColumnMap columnMap, ColumnMapTranslatorTranslationDelegate translationDelegate) 
        {
            return translationDelegate(columnMap); 
        } 

        ///  
        /// SimpleCollectionColumnMap
        /// 
        /// 
        ///  
        /// 
        internal override ColumnMap Visit(SimpleCollectionColumnMap columnMap, ColumnMapTranslatorTranslationDelegate translationDelegate) 
        { 
            VisitList(columnMap.ForeignKeys, translationDelegate);
            VisitList(columnMap.Keys, translationDelegate); 
            ColumnMap newElement = columnMap.Element.Accept(this, translationDelegate);

            if (newElement != columnMap.Element)
            { 
                columnMap = new SimpleCollectionColumnMap(columnMap.Type, columnMap.Name, newElement, columnMap.Keys, columnMap.ForeignKeys);
            } 
            return translationDelegate(columnMap); 
        }
 
        /// 
        /// VarRefColumnMap
        /// 
        ///  
        /// 
        ///  
        internal override ColumnMap Visit(VarRefColumnMap columnMap, ColumnMapTranslatorTranslationDelegate translationDelegate) 
        {
            return translationDelegate(columnMap); 
        }

        #endregion
    } 
}

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
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